Process for producing alcohols



Patented Feb. 16, 1937 UNITED STATES PATENT OFFICE du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application November 14, 1934, Serial No. 752.938

88 Claim.

This invention relates to a new and highly enlcient process for reducing organictcarboxyl compounds, and more particularly refers to a process for the production of alcohols from esters oft organic acids, both saturated and unsatura ed.

It is well known that carboxylated compounds such as fatty acid esters may be reduced by treat- CHaCOOCsHn-I-2CuH11OH+4Na= CaHsONa +3CuHiiONa The aforementioned process was subject to nu-- merous disadvantages in its practical operation. For instance, large amounts of hydrogen were evolved which did not enter into the reduction of the ester. A further disadvantage was that as the reaction progressed the viscosity of the reaction mixture increased, resulting in the formation of a viscous gel-like coating on the alkali metal which greatly interfered with its activity Scott & Hansley, in their copending application, Serial No. 729,900, filed June 9, 1934, have now disclosed that this process is greatly improved if the reactants are brought together in substantially the proportions indicated in the above equation, preferably in the presence of a hydrocarbon solvent. This process, while constituting a marked improvement over the. prior art, is still subject to certain limitations, particuiariy as regards yield per unit volume of apparatus used and as regards efficiency.

It is an object of the present invention to reduce organic compounds by an efllcient and simple process. A further object is to produce alcohols from organic carboxyl compounds. A still further object is to produce alcohols from esters of saturated and/or unsaturated organic acids. A still further object is to produce alcohols from higher fatty esters, including the glycerides by a process which is much more eflicient than those previously known. A- still further object is to reduce these esters'in the presence of cycioaliphatic alcohols. Additional objects will become apparent from a consideration of the following description and claims.

These objects are attained according to the herein described invention wherein organic carboxyl compounds, particularly esters of both satl urated and unsaturated organic acids are sub- :lected to treatment with an alkaliv metal and a mixture of alcohols in the presence of an inert solvent. In a more restricted form the invention is directed to the production of higher fatty al- 10 cohols from higher fatty acid esters by treating said esters in the presence of an inert solvent with an alkali metal and a reduced aromatic hydroxy compound or a mixture of reduced aromatic hydroxy compounds, said aromatic hydroxy 15 compounds having been reduced at least to such an extent that the carbon to which the hydroxyl group is attached has attached to it a hydrogen atom. In its preferred embodiment the invention pertains to the reduction of higher fatty acid 20 esters with sodium and hydrogenated cresylic 4 acid in the presence of xylene or a similar inert solvent, preferably also, the components of the reaction mass are brought together in the proportions specifled in the above equation as more 25 fully outlined in the Scott & Hansley application, referred to above.

The invention may be more readily understood by a consideration of the following illustrative so examples:

Erample 1 To 260 grams of sodium suspended in 900 grams of xylene by vigorous agitation at 105-115 C., is added a solution of 600 grams coconut oil (iodine number about 9) and 645 grams hydrogenated cresylic acid in 450 grams xylene over a period of about two hours. After addition of the xylene solution of the oil and hydrogenated cresylic acid the mass is agitated for about 15 4!! minutes more, and is then blown with nitrogen into water. The drowned mass is agitated a few minutes to insure complete hydrolysis of the sodium alcoholates, and the upper layer which consists of a xylene solution of the alcohols and 5 hydrogenated cresylic acids, is separated from the lower caustic soda solution. The xylene and hydrogenated cresylic acids are recovered and separated from the higher alcohols by fractionation. A 'yield of 450-470 grams of distilled higher primary alcohols (iodine number 9.5) is obtained.

Example 2 To 200 grams of sodium suspended in 1000 grams of xylene is added a solution of 850 grams the means of carrying? out the present invention.

These examples may be varied within wide limits, both as respects the materials reacted and as respects the conditions under which they are reacted. For instance, in place of the coconut and sperm oils used in said examples, other synthetic or natural oils, fats andior waxes may be substituted or used in admixture therewith. The aforementioned raw materials may be saturated or unsaturated, and may be composed in whole or in part of glycerin esters, lower alkyl esters and/or higher alkyl esters. A few of the mate'- rials which have been reduced by this method are olive oil, cottonseed oil, corn oil, rape-seed oil, peanut oil, cod liver oil esters, beef tallow, lard oil, menhaden oil, linseed oil, soya beanoil, tung oil, resin esters, palm kerneloil, China-wood oil, spermaceti, methyl ester of acids from Chinawood oil, etc. In general, these materials may be considered as obtainable from vegetables, fish and animals. However, they are not limited thereto, since they may be synthetically prepared or obtained from some other sourcesl well known to one familiar with the art. The process has been successfully applied to the hydrogenation of the esters of both chain acids and ring acids, ranging in carbon atoms per molecule from 6 to 22 and having widely varying degrees of unsaturation.

It has already been stated that the invention consists primarily in the use of a mixture of alcohols. Useful mixtures include both monoand polyhydric, aliphatic and alicyclic alcohols. These may be branched-chain or straight-chain alcohols and they may be primary, secondary or tertiary. The mixtures may consist of alcohols of the same or different classifications and the mixtures may contain alcohols in all proportions.

As stated in the Scott 8: Hansley application, referred to above, the secondary and tertiary alcohols are to be preferred as are the alcohols of higher molecular weight. It has now been found that particularly good results are obtained if alicyciic alcohols are used. These are obtained, for example, by hydrogenating phenols, i. e., aromatic hydroxy compounds to such an extent that the compound contains at least one cohols speciflcallvmentioned, herein.

Specific alcohols which may be used in admixture with other .hydrolytic alcoho s in u e methyl, ethyl, propyl, both normal and iso, prim ry. secondary, and tertiary butyl, the amyl alcohols, the higher molecular alcohols, such as octyl, nonyl, decyl, etc. up to oleyl, stearyl and higher, as well as cyclohexanol, decahydronaphthol, methyl hexanol, benyland aliphatic alcohols generally containingaromatic substituents. hydrogenated cresol and xylenol, and other bydrogenated alkyl phenols, octadecandiol and triol, alcohols produced by hydrogenating naphthenic acids, or hydroxyl compounds of the benzene naphthalene, diphenyi, diphenylamine,

azobenzene, carbazole, anthraquinone etc. series and many others. It is to be understood as mentioned above, that the hydrolytic alcohols produced by hydrogenating aromatic compounds, preferably, should at least be hydrogenated to the point where a hydrogen atom has been added to one carbon atom to which a hydroxyl group is attached. It may be mentioned that the presence of inert substituted groups on the alcohols is not objectionable, the only requirement being that the material to be used in'the process be an alcohol.

The hydrogenation mentioned above is of two types (1) acids to alcohols and (2) aromatic compounds to aliphatic compound. Each of these types are well known, however, and any convenient process may be employed.

Exceptionally satisfactory results have been obtained by utilizing as the hydrolytic agent hydrogenated cresylic acid, commonly referred to in commerce as methyl hexalin. Cresylic acid comprises chiefly ortho, meta and para cresol. It may in addition to the aforementioned cresols contain compounds such as phenol and the vari-- ous isomers of xylenol. Likewise, the boiling range of the cresylic acid, and consequently of the hydrogenated product may vary widely, depending on the relative proportionsof the different constituentspresent therein. Methyl hexalin having a boiling range of, for example, 165-180" C. has been found quite satisfactory. The preferred embodiment of the invention involves the use of cresylic acid to which has been added by hydrogenation, 6 atoms of hydrogen per mol. of

cresylic acid. However, the invention is not restricted thereto and may be practiced with hydrogenated cresylic acids having various boiling ranges, either above or below the aforementioned figures. In addition to the hydrogenated or partially hydrogenated cresylic acids, as previously mentioned, other aromatic hydroxylated compounds which have been at least partially hydrogenated to produce cyclic alcohols may be used. Hydroxyl compounds of the benzene series are of particular value in this connection, and after being converted to cyclic alcohols of the benzene series by hydrogenation treatment may be used with very satisfactory results.

The reaction which is. the subject of this invention is preferably carried out in the presence of an inert solvent. Inert solvents are well known to one familiar with the art, however, and consequently need not be discussed in detail herein. Hydrocarbons have been found to be quite useful in this connection, and in particular xylene, toluene and petroleum naphtha. The solvent may be a single chemical individual or it may consist ofa mixture. In general, the amount of inert solvent may vary within wide limits, but is advisably sufficient to prevent an excessive increase in the viscosity of the reaction mixture. In place of or in addition to sodium, other alkali metals may be used. For example, potassium alone or in admixture with sodium may be used as one of the reactants.

In the practical application of this invention it is advisable. but not essential, that the hydrolytic alcohol and the ester or esters to be reduced be present in approximately theoretical proportions. For example, where amyl acetic ester is to be reduced 2 mole of monohydric alcohol will be used for one mol. of the ester. Likewise. it is advisable that the amount of alkali metal be selected in accordance with the theoretical proportions required by the equation previously given. In the case where amyl acetic ester is reduced, this would require four atoms of sodium. Under ordinary conditions, double bonds in a fatty acid ester or other organic compound would not be attacked by the herein doscribed sodium reduction process. However, where conjugate double bonds are present one of such 2 bonds would be replaced by hydrogen. In such case, the amount of alcohol and alkali metal used should be increased to allow for reaction with one of the conjugate double bonds. Where an ester of glycerin is to be reduced three times as much hydrolytie alcohol and alkali metal will be necessary as if the ester contained onlyone carboxyl group.

A very satisfactory manner of carrying out this reduction is to suspend the alkali metal, for in-" stance sodium, in an inert solvent, for instance xylene. To this suspension is then added a suspension of a fatty acid ester, for instance sperm oil, and such. a mixture of hydrogenated aromatic hydroxy compounds as is specified above and. for

instance, hydrogenated cresylic acid, in an inert solvent, for instance xylene. The proportion of' the individual components would preferably approximate the theoretical. The temperature of the reaction should advisably be maintained above #10 the melting point of the alkali metal, temperatures of from 100-1 10 C. being quite satisfactory when sodium is used as said metal. when the reaction is completed traces of unreacted sodium may be decomposed by adding to the reaction mixture small amounts of a compound such as a lower aliphatic alcohol. The resulting product may then be converted to the free alcohol by hydrolysis, such hydrolysis being facilitated bv the presence of an acid. Finally, the free alcohols may be advantageously obtained from the hydrolyzed product by fractional distillation.

Bymeans oi this invention a-sodium reduction process is made available which permits the production of alcohols in amuch more economical manner than was heretofore possible. The use of alcohol as a solvent may be entirely elimi-.

hated, and likewise the use of excess alkali metal is made unnecessary. While superand sub-atmospheric pressures may be utilized they are not essential since the reaction progresses quite smoothly under atmospheric pressure. The production of normal primary alcohols as well as manymther types alcohols is carried out with a tremendous saving. Alcohols such as octyl.

decyl, lauryl, myristyl, cetyl, stearyl, oleyl, ri-

dium efilciency, greater ease in recovery of the product and greater fluidity of the reaction mass. The latter comparison is based on the production per unit volume of solvent. The increased sodium efliciency is attributed to the slow rate at which the sodium reacts with the 'hydrolytic alcohol, thus permitting the reduction reaction to proceed without the evolution of appreciable quantities of gaseous hydrogen. Recovery of the catalytic alcohols is also rendered more easy, particularly where the alcohol used is cyclic. since these alcohols are insoluble in water and collect in the hydrocarbon. solvent from which they are readily separated by fractional distillation. When hydrogenated cresylic acid, for example, is used no constant boiling mixtures of water and hydrolytic alcohol are formed as is frequently the case where the water soluble alcohols are used. A particularly important advantage of the use of mixtures results from the fact that where a mixture is used the reaction mass is 'much more fluid and thus a greater quantity of ester may be hydrogenated in a given volume of solvent. This advantage is especially apparent where a single ester is being reduced.

Frequently in such cases, the use of a mixture,

such-as hydrogenated cresylic acid, has been observed to permit twice as much ester to be re-- duced in a given volume of solvent. The term "hydrolytic-alcohol" in the present specification and claims is understood to mean an alcohol which when contacted with sodium in the presence of an inert hydrocarbon solvent undergoes a reaction whereby hydrogen is evolved and a sodium alcoholate is formed.

It is apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof and, therefore, it is not intended to be limited except as indicated in the appended claims.

We claim:

l. A process for producing alcohols which comprises treating an ester of a fatty acid with an alkali metal and a hydrogenated aromatic hydroxy compound having in the ring at least one carbon atom to which is attached onehydroxyl group and one hydrogen atom in the presence of a solvent inert towards the alkali metal.

2. The process of claim 1 further characterized in that the reactants are present in substantially theoretical proportions.

3. A process for producing alcohols which comprises treating substantially theoretical proportions of an ester of a fatty acid having from 6 to 22 carbon atoms with an alkali metal and a hydrogenated aromatic hydroxy compound having in the ring at least one carbon atom to which is attached one hydroxyl group and one hydrogen atom in the presence of a solvent inert towards the alkali metal.

4. The process for producing alcohols which comprises treatingan ester of a fatty acid with an alkali metal and hydrogenated cresylic acid in the presence of a solvent inert towards the alkali metal.

5. A process for producing alcohols which comprises treating substantially theoretical propor-,

tions of an ester of a fatty acid'having from 6 to 22 carbon atoms withan alkali metal and hydrogenated 'cresylic acid in the presence of a solvent inert towards the alkali metal.

6. A process for the reduction of a fatty acid ester which comprises reacting said ester with an alkali metal and a mixture of hydrolytic alcohols in the presence of a solvent inert towards the alkali metal, the proportion .of hydrolytic a1- cohols being so. chosen that the fluidity oi the reaction mass is appreciably greater than it would have been if a single hydrolytic alcohol were used. I

'7. The process of claim 6 wherein the ester.

hydrolytic alcohols and alkali metal are present in approximately stoichiometric proportions.

8. A process for the reduction of a fatty acid ester containing from 6 to 22 carbon atoms which comprises reacting said ester with an alkali metal and a mixture of hydrolytic alcohols in the presence of a solvent inert towards the alkali metal,

the proportion of hydrolytic alcohols being so chosen that the fluidity of the reaction mass is appreciably greater than it would have been if a single hydrolytic alcohol were used.

9. The process of claim 8 wherein the ester, hydrolytic alcohols and alkali metal are present in, approximately stoichiometric proportions.

10. A process for the reduction of a fatty acid ester containing from 6 to 22 carbon atoms which comprises reacting said ester with sodium and a mixture of hydrolytic alcohols in the presence of a solvent inert towards sodium, the proportion of hydrolytic alcohols being so chosen that the fluidity of the reaction mass is appreciably greater than it would'have been if a single hydrolytic alcohol were used.

11. The process of claim 10 wherein the ester, hydrolytic alcohols and sodium are present in approximately stoichiometric proportions.

12. A process for'the reduction of a fatty acid ester containing from 6 to 22 carbon atoms which comprises dissolving in a solvent inert towards sodium said ester and a mixture of hydrolytic alcohols, then reacting the resulting solution with a suspension of sodium in a solvent which is inert to the sodium, the proportion of hydrolytic alcohols being so chosen that, the fluidity of the reaction mass is appreciably greater than it would have been if a singlehydrolytic alcohol were used.

13. The process of claim 12 wherein the ester. hydrolytic alcohols and sodium are present in approximately stoichiometric proportions.

14. A process for the reduction of a fatty acid ester containing from 6 to 22 carbon atoms which comprises dissolving in a solvent inert towards sodium said ester and a mixture of hydrolytic alcohols, wherein at least one of the hydrolytic alcohols is of cyclic character, then reacting the resulting solution with a suspension of sodium in a solvent which is inert to the sodium, the proportion of hydrolytic alcohols being so chosen that the fluidity of the reaction mass is appreciably greater than it would have been if a single hydrolytic alcohol were used. I a

15. The process of claim 14 wherein the ester, hydrolytic alcohols and sodium are present in approximately stoichiometric proportions.

16. A process for the reduction of a fatty acid ester containing from 6 to 22 carbon atoms which comprises dissolving in a hydrocarbon solvent inert towards sodium said ester and a mixture of alicyclic hydrolytic alcohols, then reacting the resulting solution with a suspension of sodium in a hydrocarbon solvent which is inert to the sodium, the proportion of hydrolytic alcohols being so chosen that the fluidity of the reaction mass is appreciably greater than it would have been if a single hydrolytic alcohol were used.

17 The process of claim 16 wherein the ester, hydrolytic alcohols and sodium are presentin approximately stoichiometric proportions.

18. A process for the production of higher fatty alcohols from cocoanut oil which comprises dissolving in a hydrocarbon solvent inert towards sodium cocoanut oil and a mixture of hydrolytic alicyclic alcohols, then reacting the resulting solution with a suspension of sodium in a hydrocarbon solvent which is inert to the sodium,-the proportion of hydrolytic alcohols being so chosen that the fluidity of the reaction mass is appreciably greater than it would have been if a single hydrolytic alcohol were used.

19. The process of claim 18 wherein the cocoanut oil, hydrolytic alcohols and sodium are present in approximately stoichiometric proportions.

20. A process for the production of higher fatty alcohols from cocoanut oil which comprises reacting a xylene solution of cocoanut oil and methyl hexalin' with a xylene suspension of sodium, drowning the reaction mixture and removing therefrom the layer containing free higher fatty alcohols, and finally subjecting said layer to fractional distillation to obtain the higher fatty alcohols.

21. The process of claim 20 wherein the cocoa- .nut oil, methylhexalin and sodium are present in approximately stoichiometric proportions.

22. A process for the production of higher fatty alcohols from sperm oil which comprises dissolving in a hydrocarbon solvent inert towards sodium sperm oil and a mixture of hydrolytic alicyclic alcohols, then reacting the resulting solution with a suspension of sodium in a hydro- .carbon solvent which is inert to the sodium, the

proportion of hydrolytic alcohols being so chosen that the fluidity of the reaction mass is appreciably greater than it would have been if a single hydrolytic alcohol were used.

23. The process of claim 22 wherein the sperm 2 oil, hydrolytic alcohols and-sodium are present in approximately stoich'iometric proportions.

24. A process for the production of higher fatty alcohols from sperm oil which comprises reacting axylene solution of sperm oil and methyl hexalln with a xylene suspension of sodium, drowning the reaction mixture and removing therefrom the layer containing free higher fatty alcohols, and flnally subjecting said layer to fractional distillation to obtain the higher fatty alcohols.

25. The process of claim 24 wherein the sperm oil, methyl hexalin and sodium arepresent in approximately stoichiometric proportions.

26. A process for the reduction of higher fatty acid esters wherein the fatty acid radical contains from 6 to 22 carbon atoms which c prises dissolving in a hydrocarbon solvent inert towards sodium said esters and alicyclic alcohols corresponding to the hydrogenation products of cresylic acid, then reacting the resulting solution with a suspension of sodium in a hydrocarbon solvent inert towards sodium. f

27. The process of claim 26 wherein the ester, alicyclic alcohols, and sodium are present in approximately stoichiometric proportions.

28. A process for the reduction'of higher fatty acid esters wherein the fatty acid radical contains from 6 to 22 carbon atoms which comprises dissolving in a hydrocarbon solvent inert towards sodium said esters and methyl hexalin, then reacting the resulting solution with a suspension of sodium in a hydrocarbon solvent inert towards sodium.

29. The process of claim 28 wherein the ester, alicyclic alcohols, and sodium are present in approximately stoichiometric proportions.

30. A process for the reduction of higher fatty acid esters wherein the fatty acid radical contains from 6 to 22 carbon atoms which comprises dissolving in a hydrocarbon solvent inert towards sodium said esters and an alicyclic alcohol, then reacting the resulting solution with a suspension of sodium in a hydrocarbon solvent inert towards sodium.

31. The process of claim 30 wherein the ester, alicyclic alcohols, and sodium are present in approximately stoichiometric proportions.

32. A process for the reduction of higher fatty acid esters wherein the fatty acid radical contains from 6 to 22 carbon atoms which comprises dissolving in a hydrocarbon solvent inert towards 10 sodium said esters and an alicyclic alcohol corresponding to the hydrogenation products of a droxy benzene compound, then reacting the resuiting solution with a suspension of sodium in a hydrocarbon solvent inert towards sodium.

33. The process of claim 32 wherein the ester, alicyclic alcohols, and sodium are present in approximately stoichiometrlc proportions.

CLYDE O. HENKE. ROLAND G. BENNER. 

